A known vehicle door lock device includes a mechanism for prohibiting a release of engagement between a vehicle door and a vehicle body by means of an operation of a door handle. Such the vehicle door lock device is disclosed in JP2003-328623A. The door lock device disclosed is equipped with a child lock mechanism (i.e. a child proof mechanism) for prohibiting a release of engagement between a vehicle door and a vehicle body by means of an operation of an inside handle.
Precisely, as sown in FIG. 14, the vehicle door lock device disclosed includes a housing 101, an inside lever 102 arranged on the housing 101 and operated in association with the inside handle of the vehicle door, an open lever 103 linked to a latch mechanism for engaging the vehicle door with the vehicle body, and a child lock lever (i.e. a child proof lever) 104 for performing an operation such that an unlocked state in which the latch mechanism is operated by means of an operation of the inside handle, and a child lock state (i.e. a child proof lock state) in which the latch mechanism is inoperative by means of the operation of the inside handle are switched therebetween. In this case, the inside lever 102 and the open lever 103 are provided on respective faces of the housing 101, i.e. faces on a vehicle interior side and a vehicle exterior side. In addition, the child lock lever 104 includes an input sub-lever 104A and an action sub-lever 104B connected to the input sub-lever 104A. The input sub-lever 104A that includes an operation shaft 104Aa operated by a passenger and the like is arranged so as to be slidable and rotatable relative to the housing 101. The action sub-lever 104B includes a link shaft 104Ba on one end side, extending towards the housing 101. The link shaft 104Ba is integrally inserted into an elongated bore 102a or 102b of the inside lever 102, an elongated bore 101a or 101b of the housing 101, and an elongated bore 103a of the open lever 103.
Then, as shown in FIG. 15A, the operation of the operation shaft 104Aa causes the link shaft 104Ba of the action sub-lever 104B to vertically move in the elongated bore 102a of the inside lever 102 and the elongated bore 103a of the open lever 103, thereby switching the unlocked state and the child lock state therebetween. In this case, the link shaft 104Ba also moves in the elongated bores 101a and 101b of the housing 101 that is disposed between the inside lever 102 and the open lever 103. FIG. 15B shows a state in which the operation shaft 104Aa is operated in a downward direction and thus the link shaft 104Ba of the action sub-lever 104B is in a substantially upper end position of the elongated bore 102a of the inside lever 102 and the elongated bore 103a of the open lever 103. That is, the link shaft 104Ba is in a child lock position (i.e. a child proof lock position).
According to the aforementioned vehicle door lock device, as shown in FIG. 15B, when the inside handle is operated and thus the inside lever 102 is rotated in the counterclockwise direction in a sate in which the link shaft 104Ba of the action sub-lever 104B is in the child lock position, the open lever 103 may hit a lock link that is engageable with the open lever 103 in case of the door lock release, thereby generating a hitting noise. That is, in the state shown in FIG. 15B, a rightward movement of the link shaft 104Ba is not restricted by the elongated bore 102a of the inside lever 102 and thus the open lever 103 is rotatable in a counterclockwise direction in the elongated bore 101a of the housing 101. At this time, the elongated bore 101a of the housing 101 has a sufficient width relative to a diameter of the link shaft 104Ba. Therefore, the open lever 103 is rotatable within an angle corresponding to sufficiency of width of the elongated bore 101a relative to the link shaft 104Ba. The open lever 103 may be rotated because of vibration of the vehicle and the like, which leads to a hitting of the open lever 103 to the lock link.
Further, according to the aforementioned vehicle door lock device, the inside lever 102 and the open lever 103 are arranged on the respective faces of the housing 101, i.e. faces on the vehicle interior side and the vehicle exterior side. Then, the elongated bores 101a and 101b into which the link shaft 104Ba of the action sub-lever 104B is inserted are formed on the housing 101. Accordingly, sealing ability of the housing 101 for covering the vehicle door lock device may be reduced, which may prevent improvement of waterproof property of the vehicle door lock device.
Thus, a need exists for a vehicle door lock device that can achieve prevention of a hitting noise caused by a lever vibration and improvement of sealing ability.